Field of the Disclosure
The present disclosure relates to a quantum rod compound and a quantum rod luminescent display device including the same, and more particularly, to a quantum rod compound and a quantum rod luminescent display device including the same that is capable of improving a quantum yield, on/off driving of applying a voltage and no voltage, and color purity.
Discussion of the Related Art
Recently, flat panel displays haven been widely developed and applied to various fields because of their thin profile, light weight, and low power consumption.
Liquid crystal display devices have been widely used as representative flat panel displays.
Referring to FIG. 1, which is a cross-sectional view schematically illustrating a liquid crystal display device according to a related art, a liquid crystal display device 1 includes a liquid crystal panel 3, which comprises first and second substrates (not shown), a color filter layer (not shown) and a liquid crystal layer (not shown), a backlight unit 7, which comprises a plurality of optical sheets 5, and upper and lower polarizers 9 and 11.
Specifically, the liquid crystal display device 1 includes the liquid crystal layer (not shown), requires the optical films 52 and the polarizers 9 and 11 for embodying gray levels, and needs the color filter layer in the liquid crystal panel 3 for expressing colors.
Therefore, in the liquid crystal display device 1, light transmittance is lowered because most of light emitted from a light source (not shown) of the backlight unit 7 is blocked or absorbed when the light passes through the optical sheets 5, the color filter layer (not shown), and the polarizers 9 and 11.
That is to say, if the amount of light emitted from the light source (not shown) of the backlight unit 7 is 100%, the amount of light finally passing through the liquid crystal display device 1 may be 5% to 10%, and the liquid crystal display device 1 may have very low transmission efficiency.
Accordingly, the brightness of the light from the backlight unit 7 should be increased so that the liquid crystal display device 1 has an appropriate brightness for a display device. However, in this case, the liquid crystal display device 1 would have an increase in power consumption. Further, it is difficult to decrease the manufacturing costs of the liquid crystal display device because a lot of elements for manufacturing the liquid crystal display device are needed.
Other flat panel display devices have been researched to solve the low transmittance of the liquid crystal display device 1, to decrease the power consumption, and to lower the manufacturing costs by using fewer components.
In the meantime, organic light emitting diode display devices without the color filter layer and the optical films have been suggested to meet these demands.
An organic light emitting diode display device, which may be referred to as an organic electroluminescent display device, emits light by injecting electrons from a cathode and holes from an anode into an organic light emitting layer, combining the electrons with the holes, generating excitons, and transforming the excitons of an excited state to a ground state to emit photons.
The organic light emitting diode display device has advantages because it is able to use a flexible substrate such as plastic as a base substrate, is able to be driven by a relatively low voltage as compared to the liquid crystal display device, is superior in color representation due to self-luminescence, and is lower in power consumption.
However, the organic light emitting diode display device has a problem that its lifetime is shorter than a liquid display device because organic luminous materials of organic light emitting layers emitting various colors have different lifetimes. Especially, a blue luminous material has a relatively short lifetime.
Therefore, a flat panel display device, which has high transmittance, low power consumption, and a lifetime as long as the liquid crystal display device, is required.
Recently, quantum dots or quantum rods have been applied and developed to use in the display devices. Quantum dots or quantum rods have many possible applications due to their high luminous efficiency and superior reproducibility. A quantum dot is a semiconductor nanocrystal that can emit a narrow band of light when energized. A quantum rod is a nanocrystal with a rod-like shape.
The wavelength of fluorescence radiation emitted from a quantum dot or a quantum rod depends on its size. Namely, the quantum dot or the quantum rod emits shorter wavelength fluorescent radiation as its size is smaller. Thus, by changing the size, the quantum dot or the quantum rod can emit almost all visible wavelengths.
Also, the fluorescent radiation from the quantum rod may have a polarization property. Therefore, a display device using the quantum rod has a polarization property without a polarizer. Since the display device does not need a polarizer, there is no problem with light transmission associated with added polarizers, and the brightness of the display device is improved. Moreover, the power consumption is decreased because there is no need to increase backlight output.
In addition, the display device using the quantum rod has an advantage of an increase in its lifetime compared to an organic light emitting diode display device, which includes different organic luminous materials for respective colors and has a relatively short lifetime because the organic luminous materials have different lifetimes and properties.
However, the display device using the quantum rod has a problem of needing a high driving voltage for driving the quantum rod as compared with the liquid crystal display device and the organic light emitting diode display device.
That is, in a display device using the quantum rod, improvements in an on/off driving property and lower driving voltage are needed.